1. Field of the Invention
The present invention relates to an acoustic detection apparatus and method to acoustically detect induced circuit damage caused by semiconductor manufacturing equipment handling systems.
2. Description of the Related Art
Fabricating an integrated circuit (IC) typically includes sequentially depositing conducting, semiconducting and/or insulating layers on a silicon wafer. One fabrication step includes depositing a metal layer over previous layers and planarizing the metal layer. For example, trenches or holes in an insulating layer may be filled with a conducting metal. After a chemical mechanical polishing (CMP) planarization, portions of the conductive metal remaining between the raised patterns of an insulating layer may form, for example, vias, plugs and/or lines.
Further, semiconductor processes take place under non-typical environmental conditions of temperature, pressure, atmospheric gaseous and liquid composition, and electromagnetic field intensity that are hostile to human life. Robots in a semiconductor manufacturing and handling equipment perform a movement of the silicon wafer, which is used as a raw material for integrated circuit (IC) pattern fabrication. If a robot ceases to operate or if a mechanical component of the semiconductor processing equipment is misaligned or malfunctioning, defects of the IC pattern on the silicon wafer may occur. Such defects may include scratching from the manufacturing or handling equipment coming into contact with the wafer or particles dispersed throughout the wafer from a manufacturing environment. However, current ex-situ control of defect monitoring processes employ visual inspection and/or optical testing of the silicon wafers to detect scratching. The ex-situ control inspects the silicon wafers after the manufacturing/handling processing of the silicon wafers is complete for an entire batch of wafers, that is, outside an environment where the manufacturing/handling processing occurs. Thus, if scratching occurs during first few manufacturing operations of the manufacturing of the IC pattern on the wafer, the wafer is not inspected for defects until after a number of manufacturing operations have occurred or after the manufacturing process is complete, which could be after many hours or days.
Due to batch processing considerations and other factors introducing delay between the manufacturing and analysis of the silicon wafers for scratching, a large number of the silicon wafers may become scratched by one of the mechanical components of the semiconductor processing equipment before such scratching is detected. For instance, during IC pattern manufacturing, a cassette holds about twenty-five wafers, with one centimeter between each wafer. Further, when the defective mechanical component is identified, production is stopped and corrective maintenance is performed on the equipment, thereby a significant time delay exists between occurrence of the scratching and detection of the defective mechanical component. Thus, typically a minimum of 25 wafers—and often as many as 400 wafers or more—may be damaged or destroyed before a detection of the problem.
Conventional systems typically use optical pattern recognition to determine defects on the IC pattern. In the optical pattern recognition, a known good circuit pattern is obtained prior to the manufacturing of the IC pattern. Then, the known circuit pattern is compared with the manufactured IC patterns to then determine whether both patterns are the same. If both patterns are different, the differences are identified to determine whether the differences are scratches or particles.
Accordingly, an apparatus and method are desired that detect in-situ a failure of mechanical components of the semiconductor manufacturing and handling equipment to significantly reduce an amount of scrapped production material.